The macromolecules composing neural structures are constructed according to genetic information. We are analyzing mutations in Drosophila melanogaster to identify the genes which specify the components of the nervous system and to genetically dissect the physiological processes that these components regulate. Previous work has shown that temperature-sensitive (ts) paralytic mutants are likely to have specific defects in the nervous system. We are isolating new autosomal temperature-sensitive paralytic mutants and characterizing them genetically and behaviorally. Intracellular recordings will be performed on larval muscles to identify and analyze those mutants with defects in nerve conduction, neuromuscular transmission, or muscle response. Possible functional or physical relationships among the various gene products comprising neuronal membranes will be studied by examining genetic interactions in double mutants. Once characterized, the mutants will enable us to investigate the genetic controls which underlie the development and function of the nervous system and to eventually identify its molecular components.